Objective To learn the structure of the ovary, fallopian tube, uterus, cervix, and vagina To learn how these organs contribute to the many functions of the female reproductive system
To learn how hormones regulate and/or orchestrate the female reproductive processes
Functions of the female reproductive system • Ova production
• Ova and sperm transportation • Microenvironments for fertilization
• Implantation and fetal-placental growth • Nourishment and support of offspring • Postnatal repetition
Ovulation Rupture of follicle – Mechanism unknown collagenase, protease, plasmins – Not pressure related
Oocyte surrounded by zona pellucida & corona radiata – Lost at ovulation in cow
– Lost after sperm penetration in most species
After ovulation, the corpus luteum develops from remains of the follicular wall after ovulation.
Corpus Luteum - yellow body Corpus hemorrhagicum – transitory structure caused by hemorrhage into ruptured follicle
Corpus Luteum - yellow body
Luteinization of granulosa and theca cells to luteal cells
Corpus Luteum - yellow body Granulosa lutein cells - granulosa cells proliferate, hypertrophy, and transform – (Yellow lipid pigment - lutein marks transitory membrana granulosa cells into granulosa lutein cells)
Corpus Luteum - yellow body (Invasion of stromal cells and vasculature removes clot, deposition of reticular fibers, highly vascularized) Theca lutein cells - lipid producing cells formed from theca folliculi interna Fate relates to pregnancy – If not pregnant: slow regression corpus albicans – If pregnant: active for all or to various time during pregnancy
Ovarian Hormones Androgens – LH stimulation causes theca interna cells to produce androgens (androstenedione and testosterone) Estrogens – FSH stimulation causes membrana granulosa cells to produce estrogens (estradiol - 17b) • Granulosa cells aromatize androgens from theca interna cells to produce estrogens • Estrogens - induce further proliferation of granulosal cells
Ovarian Hormones Inhibition of FSH – Folliculostatin - inhibitory substance has negative feedback on FSH – Steroidsthemselves work through negative feedback Progesterone - granulosa lutein cells of corpus luteum – Uterine gland development – Maintenance of pregnancy Relaxin - produced by corpus luteum – Causes relaxation of ligaments associated with pubic symphysis before partarition
Oogenesis - formation and development of ova Mitosis (oocytogenesis) – oogonia – Prenatal development (ruminants, rodent, swine, human) – Postnatal development (carnivores)
Oogenesis - formation and development of ova Meiosis – oocytes Early development Maturation arrest (dictyate step of meiotic prophase) Later development synchronized with development and maturation of follicles Division • First meiotic division – reduction division – first polar body • Second meiotic division – equational division – second polar body
Fertilized 1n
Meiosis Zygote
Meiosis (only in spermatogenesis and oogenesis) Exchange of genetic material in homologous chromosomes (leptotene, zygotene, pachytene, and diplotene steps of development) Produces haploid condition of gametes
Meiosis (only in spermatogenesis and oogenesis) Produces haploid condition of gametes
Species difference in time of polar body formation Polar body extrusion
many mammals
horse and dog
First
preovulation
postovulation
Second
zona penetration
zona penetration
of sperm
of sperm
First polar body
Birth
Follicular development - synchronized with gamete development
Other glands of epidermal origin – mammary gland Gland for which our class, mammalia, was named. Mammals are characterized by hair on skin, special ear bones, and in females, milk-producing mammary glands for nourishment of young.
